Such components are configured as, for example, connecting rods having one small connecting rod eye, one large connecting rod eye and a shaft, the large connecting rod eye having a split bearing seat for supporting the connecting rod on the crankshaft. Because the invention relates in particular to the production of a connecting rod, the discussion below is devoted primarily to a connecting rod, but only by way of example and not by way of limitation.
A connecting rod is generally produced in that first a preform is produced, for example by means of forging, casting or powder-metallurgy methods; the inside dimension of the large connecting rod eye has an overdimension in the region of the future separation point. At this location the large connecting rod eye is separated, for example by means of sawing, extensively eliminating the overdimension. On the one hand, the separation surfaces of the connecting rod cap formed in this way and, on the other hand, the remainder of the connecting rod, are processed in a further method step, for example by means of grinding, so as to fit together precisely. In its finished state, the connecting rod cap is attached to the remainder of the connecting rod by means of connecting rod screws; the screw holes required for these can be bored prior to or following separation. In the assembled state of the connecting rod, the mechanical processing of the bearing seat is subsequently effected to receive bearing shell halves, which are disposed between connecting rod and crankshaft, forming a slide bearing.
The mechanical processing of the bearing seat usually encompasses rough-machining, fine-machining and superfinishing, by means of turning, precision-turning or honing. Furthermore, recesses must be provided in the bearing seat of the connecting rod eye which cooperate with corresponding latches of the bearing shell halves to prevent relative rotation of the bearing shells during operation.
In particular, the two bearing shell halves must be produced with high precision, because on the one hand the inside surfaces of the bearing shell halves, together with the crankshaft, form the slide bearing with a necessary slide bearing fit, and on the other hand, the outer surfaces of the bearing shells must be adapted to the bearing seat of the large connecting rod eye of the connecting rod. To assure a secure seating of the bearing shell halves, it is necessary, among other things, that the bearing shell halves be clamped between the connecting rod cap and the remainder of the connecting rod. It cannot be ruled out here that, when the connecting rod cap is screwed on and thus the bearing shell halves are clamped, deformations and thus removal of material will occur, the consequence of which is imprecise fitting of the inner surface of the bearing shell halves.
Despite the most careful processing and high fitting precision, it cannot always be avoided that, for example, the connecting rod cap is displaced on the remainder of the connecting rod because of the extremely high stresses of a connecting rod during operation, and thus a perfect seating of the bearing shell halves is no longer assured. Moreover, it is possible that the bearing shells still rotate despite measures against relative rotation. This inevitably leads to destruction of the slide bearing and thus to a breakdown of the motor.
A connecting rod is known from DE-PS 38 06 236 whose connecting rod cap is separated from the remainder of the connecting rod by means of fracture separation. In this case a fracture surface having a large, irregular surface is created as the separation surface, which virtually excludes a lateral displacement of the connecting rod cap on the remainder of the connecting rod. Furthermore, it is accomplished that only the respective connecting rod cap separated from the preform can be attached to the respective remainder of the connecting rod, because the fracture surface is unique, which rules out a confusion of individual parts, for example during assembly or repair of the motor. As before, however, bearing shells must be inserted into connecting rods produced in this way, because the material from which the connecting rod is made is not suitable as a slide bearing material. Therefore, the danger arises that the bearing shells rotate in the bearing seat, despite the measures against relative rotation to be likewise provided in the form of recesses and latches in the bearing seat, and have as a consequence a breakdown of the motor.
The object of the invention is to create a component, for example a connecting rod having a split bearing seat, in which the above-named disadvantages are avoided to the greatest extent.